Introduction: Hyperglycemia mediates the production of excess free radicals and reduces endogenous antioxidant in type 2 diabetes mellitus (T2DM). Black soybean (BSB) is rich in antioxidant mainly from isoflavones, whereas the antioxidant of purple sweet potato (PSP) comes from high anthocyanin. The study aimed to evaluate the efficacy of BSB, PSP, and its combination on malondialdehyde (MDA), superoxide dismutase (SOD) concentrations, insulin and insulin receptor substrate-1 (IRS-1) expression in T2DM rats. Methods: T2DM induced by high-calorie diet for five weeks and then injected with a low dose of streptozotocin (30 mg/kg BW) intraperitoneally. The DM rats then treated with black soybean (DM + BSB), purple sweet potato (DM + PSP) and the combination of BSB and PSP 1:3, 2:2, 3:1 respectively (DM + C1-3). Treatments were given for thirty days. The effect of BSB, PSP and its combination evaluated by measuring SOD and MDA, necrosis in pancreas evaluated through hematoxylin-eosin (HE) and insulin and IRS-1 expression in pancreas through immunohistochemistry-fluorescence (IHC-F). Results: Our result indicated that there were no significant differences of BSB and the combination in decreasing MDA concentrations. The ratio of BSB and PSP combination of 2:2 increase SOD towards near normal, decrease necrosis, and improve insulin and IRS-1. Conclusion: The combination of BSB and PSP had the potential to improve insulin sensitivity through the increase of SOD, reduce necrosis, and improve insulin and IRS-1 expression. and Natural Sciences, Brawijaya University, Indonesia. Her research interest field is nutrigenomic. Currently, she has a research projects about garlic and their impact for health.

Overproduction of reactive oxygen species (ROS) will promote oxidative damage and can induce reproductive disorder. A therapeutic strategy to reduce effects of reproductive disorder is by maintaining the balance between ROS and antioxidants. Black soybean (BSB) contains phenolic compounds and has a greater antioxidant capacity than yellow soybean. Purple sweet potato (PSP) also has antioxidant capacity, due to the presence of anthocyanin, but is low in protein. The combination of BSB and PSP is expected to limit symptoms of reproductive disorder through decreasing ROS levels, enhancing testosterone production, and improve sperm quality. The results of this study indicate that the combination of PSP and BSB could restore blood glucose levels, improve seminiferous tubules diameter, decrease ROS production, and improve testosterone and sperm quality. A ratio of BSB to PSP of 2:2 and 3:1 were effective to improve symptoms of reproductive disorder in the type 2 diabetes mellitus (T2DM) rat model.